<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>

    <div style="position: relative;width: 500px;height: 200px;border: 1px solid red;margin: 0 auto;">
        <div style="position: absolute;left:0;bottom:0;width: 50px;height: 50px;background-color: black;"></div>
    </div>
    <div style="position: relative;width: 500px;height: 200px;border: 1px solid red;margin: 0 auto;">

        <div style="position: absolute;right:0;bottom:0;width: 50px;height: 50px;background-color: black;"></div>
    </div>
    <div style="position: relative;width: 500px;height: 200px;border: 1px solid red;margin: 0 auto;">

        <div style="position: absolute;right:0;top:0;width: 50px;height: 50px;background-color: black;"></div>
    </div>
</body>
</html>